On my last birthday last April my wife (god bless her!) bought me a Seagull Ultimate 43" span ARTF. It was my original intention to fit my OS46AX 2 stroke in it. However nothing got done over the summer (Sheer idleness I'm afraid). During a visit to the Bullodrome (Rollestone Model Flying Consortium) John Miller and I met with a flyer who put us on to the http://www.hobbycity.com/hobbycity/store/uh_index.asp website saying that is was a very good source of electric flight essentials. This got me into thinking that perhaps I could electrify the Ultimate. I went on the site and priced up the required parts. This came to £236 for the motor, speed controller and 4 batteries. Right, I thought, lets have a go!!
The only modification to the airframe was to graft on an extended firewall for the motor, carve a hole in F! so that battery would slide in and to cut away some of the cowl to allow access to fit the battery and give some extra cooling. The weight turned out to be 3.1Kg, just under the top specified, and the C of G was in the correct location.
The power train was then tested and at full chat nasty noises emanated from the motor!! A read of the manual was done and it was decided to set the timing of the Speed Controller to high. This did the trick. I had to wait a few days for the test flight on Sunday 6th September. After a range check it was into position for a take off with John (Miller) on my shoulder to give words of encouragement and operate the trims if necessary. The taps were opened to about 60% and the model surged forward and fairly leapt into the sky. A couple of right trim clicks were all that was required for stable flight. After 8 minutes I landed and noticed a problem common to a lot of ARTFs namely a crappy undercarriage. This was bent back to shape and the battery recharged. A second flight was achieved with no problems.
By Wednesday my further 3 batteries arrived so it was off to the patch for some more fun. A prop speed check indicated about 8,300 rpm and a power check showed that the motor was receiving 1.1 kilowatt! Four enjoyable flights were had and even a die hard IC man seemed slightly impressed!!
Friday, I'm afraid the model met its match in a dog fight with a Gemini and both pilots were buried with full military honours! A phone call to the Hobby Hangar found that they had an Ultimate in stock so on the excuse of taking the wife out for the afternoon it was off to Yeovil to exercise my plastic.
By Tuesday the new version was ready for its test flight and this was accomplished with out a problem except for the afore mentioned weak undercarriage. John (Miller) suggested that I fabricate some U/C legs from some 3.5mm hard alloy he had. This has now been done and will be tested shortly.
The specification is as follows:-
Base Model - Seagull Ultimate 43" span
Servos (5) - Futaba 148 & 3001
Motor - TURNIGY 50-55B 600kv Outrunner http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=4907
Speed Controller - TURNIGY Plush 80A w/ UBEC Speed Controller http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=3727
Battery - Turnigy 5000mAh 5S 20C Lipo Pack http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=9174
Propeller - EMF 14 x 8E
Max RMP 8,300 approx
Power Drawn 1.1 Kilowatt
Rod Watts